At its longest point, how many miles is the yamato core area

 101 miles

The Yamato Core is a shallow ice core in the eastern region of Antarctica.  The Yamato Mountains were first observed and photographed from the air in 1960 by an expedition team from Belgium, who named the mountains the Queen Fabiola Mountains, after the Queen of Belgium at that time.  The Japanese Antarctic Research Expedition made the first visit and geological exploration of the mountains a few months later, in 1960, and gave the name Yamato Mountains to the region.